The overall objective of the Animal Models and Pathology Facilities Core is to provide Center members with state-of-the-art pathology support, transgenic resources and a centrally-managed AAALAC-approved animal holding and surgical facility. The Core is staffed with experienced personnel and is equipped with essential equipment to generate genetically engineered mice (GEM), rederive imported mice by embryo transfer rederivation, provide colony management, and prepare and interpret tissue samples by histological and image analysis. The specific aims are as follows: (1) To generate transgenic animals by pronuclear microinjection of DNA constructs or embryonic stem cell manipulation and provide colony management of GEM for use by Center members; (2) To rederive transgenic and other specialized mouse strains by embryo transfer to assure specific pathogen free status of all mice used in this program; (3) To provide histology, pathology, molecular characterization and imaging expertise for extensive phenotyping and assessment of pathological damage of GEM and other animal models as needed.